President Obama accused Republican senators Thursday of setting the U.S. courts system “on a dangerous course” that could leave the federal bench half empty within a decade if they continue to block his judicial nominees.

“Proceeding this way will put our judiciary on a dangerous course, as the Department of Justice projects that fully half of the Federal judiciary will be vacant by 2020 if we continue on the current pace of judicial confirmations,” Obama writes. “The real harm of this political game-playing falls on the American people, who turn to the courts for justice. By denying these nominees a simple up-or-down vote, the Republican leadership is undermining the ability of our courts to deliver justice to those in need.”

Obama points out that the Senate has confirmed fewer than half of his judicial nominees, yet by this point in the first term of his predecessor, the Senate had confirmed 61 percent of George W. Bush’s. 23 judicial nominees are waiting for an up or down vote.

“The Federal judiciary and the American people it serves suffer the most from this unprecedented obstruction,” Obama wrote. “Despite the urgent and pressing need to fill these important posts, a minority of Senators has systematically and irresponsibly used procedural maneuvers to block or delay confirmation votes on judicial nominees – including nominees that have strong bipartisan support and the most distinguished records. The minority has even been blocking non-controversial nominees – a dramatic shift from past practice that could cause a crisis in the judiciary.”

Obama conveys his respect for the role of his former colleagues in the confirmation process and says if Senate Republicans have “a genuine concern about the qualifications of judicial nominees, that is a debate I welcome.”

“But,” he adds, “the consistent refusal to move promptly to have that debate, or to confirm even those nominees with broad, bipartisan support, does a disservice to the greatest traditions of this body and the American people it serves.”

McConnell aide Don Stewart responded to Obama's letter by blaming Democrats, including the president, for the majority of vacancies on the federal bench.

"Here’s an important factoid: There are 106 vacancies on the federal bench. There are 23 pending before the full Senate (as the president complained about in his letter) and half of those have been on the calendar for less than three legislative weeks," Stewart wrote in an e-mail. "The other 83 are not pending before the Senate. They’re either stuck in a committee that’s controlled by a Democrat—or the president hasn’t even nominated anyone yet."

Obama, he added, is "complaining about two dozen when Democrats are responsible for the other 80 percent of the vacancies."